Dr. Paul Leeland Kirk, professor of Criminalistics and forensic expert for the Sheppard defense team, stated in his affidavit that he examined the crime scene, various pieces of evidence held by the prosecutor and police, as well as blood samples collected and mailed to him. His investigation began on January 22, 1955 and continued for several months. Dr. Kirk used blood spatter analysis to conclude, among other things, that:
- The murderer was left-handed (Dr. Sam Sheppard was right-handed)
- Injuries to the victim's teeth indicate that the victim had bitten the attacker's hand
- A large bloodstain on the closet door was likely from the attacker's bloody hand
- Testing of the blood stain showed it did not match that of Sam or Marilyn Sheppard, so the attacker must have been a third person
- The murder weapon was a cylindrical object, such as a pipe or flashlight, not a surgical instrument, as asserted by the Coroner
- The physical evidence demonstrated that the crime was a sexual assault
Overhead diagram showing the pattern of stains on the walls and showing the void area.
Per Kirk's Affidavit:
"The bedroom in which the murdered body of Marilyn Sheppard was found is shown in approximate scale diagram in accompanying photograph No. 1. The diagram represents the condition at the time it was examined by the undersigned. The two twin beds and bureau, shown in the drawing are in the same position as indicated in prosecution photographs. The drawing omits the rocking chair in the northeast corner of the room, which carried no visible blood or other significant evidence, and the small telephone stand between the two beds which did not figure in testimony, or in this investigation."
Portions of wardrobe and hall doors showing "approximate limitation of blood spots on the doors"
The last of the blood spots north of the wardrobe door are approximately eight inches from the door jam facing.
The north wall was very significant in respect to blood spots. On the west offset there were approximately 10 spots that were relatively large and retained high velocity up to the time of impact. They had been thrown 10 feet or more. A similar number was also present and scattered over the east side offset on the north wall.
On the extreme east end of the (north) wall, past the offset, for about 2 feet there was an area containing no spots, and a continuation of the corresponding space on the east wall. This single region in the entire periphery of the room in which no blood traveled through the air must by necessity be the region in which the attacker stood, since it is the only place in which the blood drops have been intercepted.
Close to the edge of the bed and slightly overlapping it, the width of the cone created by measuring lines would be about 2 feet, which approximates the width of a man's body. It places the attacker very close to the foot of the bed on the east side.
Victim's bed with the covers arranged to correspond with the arrangement shown in the exhibits of the prosecution: the bloody side of the pillow upward, the pillow occupying the blood-free region of the lower sheet, and the top covers turned back so that all of the exposed area showed blood spotting. On the bed, chiefly on the exposed portion of the lower sheet, the turned-back portion of the upper sheet, and on top of the pillow, were a large number of small blood spots. On the side nearest Marilyn's bed there was a region of larger spots, none over 1/4" in diameter. Over the remainder of the bed the spots were much smaller and showed by their shape that the droplets were moving at relatively high velocity and numerous drops moved in an arc approaching the horizontal. Many of them had dropped more nearly vertically, representing higher arcs of flight.
Utilizing the spots on the defendant's bed, it was noted that all those with elongated patterns had originated at a single center of origin that corresponded to exactly the region of Marilyn Sheppard's mattress on which the blood intensity was greatest and which was occupied by her head at the time she was found. It can therefore be stated with certainty that her head was in essentially the same position during all of the blows from which blood was spattered on her bed. This distribution is illustrated in photographs 7 through 11.